Stable white oil



' able.

Patented July 10, 1934 1.960.050 s'nmm warm on.

Reginald a. Sloane, Elizabeth, Standard Oil Development ration of Delaware 86mins.

This invention relates to improved white oil products which are stable against the oxidizing action oi air.

One object of the invention is to increase the 5 value of highly refined white oils by rendering them resistant to oxidation when exposed to the air for a considerable length of time.

' Another object is to prepare superfine lubricating oils for use in steam turbines or for similar applications.

Other objects and advantages will be apparent in the course of the following description.

In many uses of oil, acidity or acid formation on its prolonged contact with air are objection- It has been considered fora long time that the degree of refining of an oil is a measure of its stability. Gurwitch. (Wissenschaitliche Grundlangen der Erdolverarbeitung (1924) pages 32-42) said that: The resistance of a petroleum 30 product to the action of the oxygen of the air is the greater the more thoroughly it has been refined with sulphuric acid. Nevertheless he also noticed the instability toward air and light of kerosene treated by oleum and filtered. Many 35 other such observations have led Gurwitch to remark that we are thus confronted by the paradox that under certain conditions too careful refining lowers the quality of an oil by making it more easily oxidizable."

5e It has been my experience with the highly refined white oils that they are especially easily attacked by the oxygen of the air and develop acidity much sooner than a similar oil which has not been refined so far. White oils, as known 35 to those skilled in the art, are prepared by extensive treatment with strong sulphuric acid of the middle fractions of crude oils, such as gas oil, light lubricating oils, etc. I have found, for instance, that on blowing air through a sample of 46) commercial grade of white oil kept at a temperature of 300 F. the acidity, expressed in milligrams of KOH per gram of the oil, increased about 3 points for every five hours of blowing while 'under the same conditions the acidity of 35 a petrolatum oil increased quite inconsiderably, its

value being somewhat less than A; point after 20 hours of air blowing. It will be understood that the oxidation of the white oils proceeds at lower temperatures too although its rate decreases with decreasing temperature. However, these oils will develop acidity even at atmospheric temperature on long exposure to air, especially in 1 summer time. v a

After having ascertained the great sensibility white oils to oxidation by air, I discovered in my further experiments the T orrica t the same oils can be rendered practically stable and non-oxidizable on exposure to air by the addition of small amounts of certain chemical compounds which may be termed fanti-oxidation catalysts". tained some inhibitory action with But the most complete ments and compounds. protection was obtained oil of higher mercaptans I have obvarious elethe addition to the such as thio-beta-naphthOL'CmH-ISH. This compoundis better called beta-naphthyl mercaptan since it does not contain the hydroxyl group and is true naphthol. This compound protection from acidity when of from 0.05-0.1%. The merca therefore not a gave complete added in an amount condensed nuclei gave also good results. The expression of complete protection is intended to means that no acidity was developed on 24 hours oxidation by blowing air through the oil at 300 F.

The white oils thus stabilized against the oxidizing action show improved characteristics when such oils are used for various p poses. One

specific use which is be specifically pointed out.

novel for such oils should I have discovered that white oils having viscosities from 85 to 360 seconds at 100" F. may be used as superfine turbine oils when they contain a small amount of an anti-oxidation catalyst.

velop sludge and acidity even temperatures and therefore very long time so that shut They will not deat high bearing ptans of other can be used for a 35 -downs for cleaning are practically eliminated. The following physical characteristics of a white oil base turbine oil are given by way of illustration:

Gravity 29.3-30.2 A. Pour 20 F.

Visc. 100 R 150-160 sec. (Saybolt Universal) Color 30+.Saybolt White oils having other characteristics may be compounded with the anti-oxidation catalyst. However, for many purposes, it is advantageous to use a white oil having a viscosity of not lessthan and not morethan 360580011118 at 100 F.

Other mercaptans than those of condensed nuclei may be used as anti-oxidation catalysts for turbine oils, it they have high molecular weights and high boiling points. Highmolecu- -iar weight compounds will not attack the copper and other metals in the turbine, and the high boiling points will insure the non-evaporation v of the anti-oxidant. As'an example of the lowest permissibie'molecular weight parafllnic' mercaptan; I have found normal heptyl mercaptan to be a moderately 800d anti -oxidant.

'trom the class consisting I. A stabilized petroieumwhite'oil composition,,comprisins a petroleum white oil and l1epv tyl mercapton.

3. A method oil aninst oxidetion,

of protecting u petroleum white which comprises mixinl mm a. gnome. 

